Topical pharmaceutical compositions are, of course, well known. They can be used as water proofing agents, sunscreens, skin conditioning agents, lip balms, wound dressings, hair pomades, etc. Regardless of the specific use, common to pharmaceutically satisfactory topical actives are that they must stay on the skin for a sufficient period of time to allow the active to perform; they must not irritate the skin; and, they must be perceived by the patient as pharmaceutically elegant or the patient will simply not use them. By “pharmaceutically elegant”, as those skilled in the art know, one means the skin feel to the patient is good. It must not be too watery or too greasy. Some say it relates to the creaminess or lubricity properties as well as ‘moisture retaining’ properties.
There is a continual need for improvements in topical carrier systems, particularly for those that are lipophilic in nature, most of which are perceived by consumers as too waxy or too greasy when smeared on the skin. This invention relates to this need.
While aerosol delivery lipophilic systems have been used for topicals before, a problem with typical aerosol systems is to develop one that does not feel greasy and which is cosmetically superior. Known non-aerosol compositions which provide a nongreasy feel in topicals can include liquid silicones such as cyclomethicone, hexamethyldisiloxane, and dimethiconol. However, such liquid silicones are recognized in the art as defoaming agents. Defoaming agents are not something that one would want to add to a topical aerosol composition where foaming is an essential part of the delivery system since they act to defoam. Surprisingly, it has been found, however, that in the current invention, a topical aerosol foam composition has been created that does contain a large quantity of liquid silicones and yet it unexpectedly produces quality foam.
This invention offers a number of other benefits to the user which are also desirable objectives. The drug delivery system in the form of foam facilitates a novel, yet efficient mode of topical drug delivery system. It also facilitates continuous product output thereby adding ease of application. When dispensed in small quantity, the drug delivery system in the form of a foam can also cover a larger surface area of application while also facilitating better product application in areas where conventional topical products cannot be as effective. The drug delivery system in the form of foam also facilitates the use of a lower dosage which can minimize adverse reactions. The other crucial benefit is that this foam form of delivery system is devoid of any contact with air, light, or any other form of contamination as this is a completely sealed system throughout the life of the product. Thus, light and oxidation prone topical actives can be preserved effectively in the aerosol system. The anhydrous system of the carrier further extends the preservation of topical actives that are otherwise easily degraded by presence of a water base.
Accordingly, it is a primary object of the present invention to prepare a topical application or pharmaceutical composition which is of widespread applicability (i.e. useful with many drug actives) and which is at the same time perceived by the user as pharmaceutically elegant.
Another objective of the present invention is to achieve the primary object with a composition especially adapted for lipophilic compounds and which can provide effective delivery in the form of a foam.
A yet further objective is to provide a method of preparation of a topical application or pharmaceutical composition in the form of a foam that achieves each of the above objectives or attributes.
The method and manner of achieving each of the above objectives as well as other objectives of the invention, will become apparent from the following detailed description of the invention.